E27 prop questions

[SV_Ariel]

Thanks for everyone’s help. I did redo my reduction. Down to 2.6 to 1 and that greatly increased the acceleration without touching the prop. I am still going to change to a three blade this winter.

Elgyn- I am using two Power Queen 25.6V 100ah, LifePO4 batteries. I can’t remember what I paid for them but I think it was somewhere around $1000 for both. My boat is on a mooring so I barely use the motor. We typically sail off the mooring then use the motor a little bit coming in. I’ve never had the batteries below 90% yet so I can’t speak to any battery lifespan.

 

[SV_Ariel]

I did switch the drive over to belt drive as well. The chain was only temporary until I figured out what final drive I needed. It is incredibly quiet now.

 

[Mark F]

Hi Elgyn, I've got two banks of LiFepo4 batteries. One at 160ah and another at 40ah. I like having two banks - backup if one has issues. 400ah should get you motoring for days ;-)

 

[Elgyn]

Good to know. I have to motor about 1.5-2hrs to get out of the Fraser river before I can do any real sailing. Also keeping a range extender(aka an outboard)on the back as the winds tend to die out in between the Gulf islands and Desolation Sound

 

[Solarken]

Can’t seem to find any info in the search bar for E27 propellers.

I have what I assume is a stock prop on my 74 E27. I have recently swapped out to a Thunderstruck EV system. I think I need a larger prop. The electric motor spins the shaft like mad but it just doesn’t seem to have any giddy up.

The boat is incredibly sluggish at initial throttle. I never ran the boat with the previous A4 so I have no frame of reference on the props performance.

At first I thought my prop had fallen off because the motor was going like mad but I barely was getting movement.

Anyway, it’s a 2 blade prop, that’s about all I know. Never measured it. I’m thinking of getting a higher torque low pitch prop, probably three blade but I don’t know what size will fit. Anyone know the diameter of the stock two blade propeller?

For years I ran a Tohatsu 6hp with the high thrust prop and it moved it really well. I thought for certain using the prop right in front of the rudder would have given me better performance.

I’m all electric. My indigo was horrible even after I had it recurved.
First question. What is your gear ratio? Motor rpm to shaft rpm?
Next item. I had a custom prop made. Can’t use a 12” because that’s ⅝” from the keel. So I had an 11” made. 3 blades 13” pitch. WoooHooo! Bites the water great! I am 1.8-1 so 1800 rpm turns the prop shaft at 1000 rpm. I usually run at 1350 rpm for about 3.5-3.8 knots and low battery draw.
im a 1975 32-2 loaded to 11,600# with gear, water, food, so on and me. 10kW electric yacht “Quiet Torque” I can do 6 knots but don’t bother unless I’m bucking wind or current.

 

[Solarken]

I’m all electric. My indigo was horrible even after I had it recurved.
First question. What is your gear ratio? Motor rpm to shaft rpm?
Next item. I had a custom prop made. Can’t use a 12” because that’s ⅝” from the keel. So I had an 11” made. 3 blades 13” pitch. WoooHooo! Bites the water great! I am 1.8-1 so 1800 rpm turns the prop shaft at 1000 rpm. I usually run at 1350 rpm for about 3.5-3.8 knots and low battery draw.
im a 1975 32-2 loaded to 11,600# with gear, water, food, so on and me. 10kW electric yacht “Quiet Torque” I can do 6 knots but don’t bother unless I’m bucking wind or current.

On a long haul in no wind I use a Honda 2kW generator to keep my charging going at 22A and I drive the boat at about 3.5 knots using 20-24A so the batteries stay pretty full. I did a 27 km crossing with no wind into light current and swells and used 2.2 gallons of gas ⛽️ in the generator. Batteries were nearly full when I arrived.

 

[Solarken]

What chemistry and size battery banks do you guys run? I'll be running 48V LiFePo4 about 400Ah.. ..maybe more

Very Big!!! Nice $$$$$

 

[Solarken]

Propeller for electric motor

www.sailnet.com

Okay
2-1 gives you double the torture at the prop. Proper gears/belt setup will cost you under 2% power loss. The added torque and less wear on cutlass bearing is a big plus. You should shoot for 1000-1100 rpm top prop shaft speed.

 

[Solarken]

I'm looking at the same 5Kw (but water cooled) system for my e29. I like my 9.9 outboard, but it's a P.I.T.A. to raise/lower. I believe a 12d x 10p 3 blade is about the largest that can fit without snapping the 3/4" shaft at the most inconvenient time and will still do any sort of regen. Not sure if that info is relevant to your e27

Regen is a small thing. Maybe 170W is the best I’ve seen.

 

[Elgyn]

Very Big!!! Nice $$$$$

I have +40, 48V 100Ah batteries sitting in a warehouse that were donated to me